This invention relates to a locked joint between pipe system components, in particular between pipes, and to a split metal retaining ring usable in a joint of this kind.
The pipe system components may be not only pipes, but also pipe system accessories, such as fittings. It will be assumed that the following description applies to pipes.
A locked joint between pipes is a fluid-tight assembly that can withstand dislocating forces that are generated when the pipe system is placed under pressure. A locked joint typically comprises a socket of a first pipe, a smooth end of a second pipe inserted in the socket with the interposition of an annular sealing gasket, a raised bead integral with the smooth end, a split retaining ring arranged around the smooth end just to the rear of the raised portion, and a rear support surface for the retaining ring integral with the socket.
The rear support surface for the retaining ring may be a mating flange at the entry to the socket. In this case, assembling the joint merely requires that the retaining ring be able to open or expand, thus allowing it to pass over the raised bead of the smooth end. In other configurations, however, the rear support surface forms a part of the socket itself and is positioned in front of an entry flange of the socket. The retaining ring must, in this case, be capable of sufficient contraction to pass under the entry flange of the socket.
One technique used to achieve sufficient contraction of the retaining ring so that it can pass over the entry flange consists in crossing the ends of the ring using an appropriate tool. This crossing arrangement requires a certain degree of flexibility of the ring, in particular under torsion.
When the diameter of the pipes is large, for example greater than or equal to 400 mm, the retaining ring may be made of metal, since the requisite elastic ductility is naturally obtained using conventional sections.
On the other hand, when small diameter pipes (&lt;400 mm) are used, the rigidity of a metal retaining ring becomes such that more flexible materials, such as plastomers, must be employed. However, although easily deformable, a locking ring made of a plastic material raises the problem of exhibiting poor pressure-resistance when the pipe system is in use. This invention is thus intended to supply a locked joint incorporating a split metal retaining ring usable within a broad range of diameters of the pipe system components, while ensuring good pressure-resistance.